WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.11 - Acetals and hemiacetds, whether or not with other oxygen function, and their halogenated, sulphonated, nitrated or nitrosated derivatives. (A) ACETALS AND HEMIACETALS Acetals may be regarded as di-ethers of (normally hypothetical) hydrates of aldehydes and ketones. Hemiacetals are mono-ethers in which the carbon-atom adjacent to the ether-oxygen atom also bears a hydroxyl group. r " Acetals and hemiacetals with other ox gen b c t i o n " are acetals and hemiacetals containin one or more of the oxygen kctions (e-g., a coho1 function) referred to in the previous headings o this Chapter. B (1) Methylal (CH2(0CH&). Dimethy1 ether of the hypothetical hydrate of formaldehyde. Colourless liquid with an ether-like odour; used as a solvent, as an anaesthetic and in organic synthesis. (2) Dimeth lacetal CH3CH(OCH3)2). Dimethyl ether of the hypothetical hydrate of acetalde yde; use as an anaesthetic. h (3) Diethylacetal (CH3CH(OC2H5)2).Also derived from the hypothetical hydrate of acetaldehyde. A colourless liquid with an agreeable ether-like odour; used as a solvent and as an anaesthetic. The heading excludes polyvinyl acetals (heading 39.05). (B) HALOGENATED, SULPHONATED, NITRATED OR NITROSATED DERIVATIVES OF ACETALS AND HEMIACETALS These are compounds obtained b who11 or partly re lacing one or more of the hydrogen atoms in the acetal by halogens (e.g., c loral a coholate, ch oropropyl acetal), sulpho groups (-S03H), nitro groups (-NO2)or nitroso groups (-NO). K I P This heading also covers any combinations of these derivatives (for example, nitrohalogenated, nitrosulphonated, sulphohalogenatedand nitrosulphohalogenated derivatives). Sub-chapter V ALDEHYDE-FUNCTION COMPOUNDS
1.- Except where the context otherwise requires, the headings of this Chapter apply only to : (a) Separate chemically defined organic compounds, whether or not containing impurities; (b) Mixtures of two or more isomers of the same organic compound (whether or not containing impurities), except mixtures of acyclic hydrocarbon isomers (other than stereoisomers), whether or not saturated (Chapter 27); (c) The products of headings 29.36 to 29.39 or the sugar ethers, sugar acetals and sugar esters, and their salts, of heading 29.40, or the products of heading 29.41, whether or not chemically defined; (d) The products mentioned in (a), (b) or (c) above dissolved in water; (e) The products mentioned in (a), (b) or (c) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (f) The products mentioned in (a), (b), (c), (d) or (e) above with an added stabiliser (including an anti- caking agent) necessary for their preservation or transport; (g) The products mentioned in (a), (b), (c), (d), (e) or (f) above with an added anti-dusting agent or a colouring or odoriferous substance or an emetic added to facilitate their identification or for safety reasons, provided that the additions do not render the product particularly suitable for specific use rather than for general use; (h) The following products, diluted to standard strengths, for the production of azo dyes : diazonium salts, couplers used for these salts and diazotisable amines and their salts. 2.- This Chapter does not cover : (a) Goods of heading 15.04 or crude glycerol of heading 15.20; (b) Ethyl alcohol (heading 22.07 or 22.08); (c) Methane or propane (heading 27.11); (d) The compounds of carbon mentioned in Note 2 to Chapter 28; (e) Immunological products of heading 30.02; (f) Urea (heading 31.02 or 31.05); (g) Colouring matter of vegetable or animal origin (heading 32.03), synthetic organic colouring matter, synthetic organic products of a kind used as fluorescent brightening agents or as luminophores (heading 32.04) or dyes or other colouring matter put up in forms or packings for retail sale (heading 32.12); (h) Enzymes (heading 35.07); (ij) Metaldehyde, hexamethylenetetramine or similar substances, put up in forms (for example, tablets, sticks or similar forms) for use as fuels, or liquid or liquefied-gas fuels in containers of a kind used for filling or refilling cigarette or similar lighters and of a capacity not exceeding 300 cm3 (heading 36.06); (k) Products put up as charges for fire-extinguishers or put up in fire-extinguishing grenades, of heading 38.13; ink removers put up in packings for retail sale, of heading 38.24; or (l) Optical elements, for example, of ethylenediamine tartrate (heading 90.01). 3.- Goods which could be included in two or more of the headings of this Chapter are to be classified in that one of those headings which occurs last in numerical order. 4.- In headings 29.04 to 29.06, 29.08 to 29.11 and 29.13 to 29.20, any reference to halogenated, sulphonated, nitrated or nitrosated derivatives includes a reference to compound derivatives, such as sulphohalogenated, nitrohalogenated, nitrosulphonated or nitrosulphohalogenated derivatives. Nitro or nitroso groups are not to be taken as “nitrogen-functions” for the purposes of heading 29.29. For the purposes of headings 29.11, 29.12, 29.14, 29.18 and 29.22, “oxygen function”, the characteristic organic oxygen-containing group of those respective headings, is restricted to the oxygen-functions referred to in headings 29.05 to 29.20.